The folding structure and the locking device are the key parts of a foldable container. The corner posts facilitate the folding down of the folding structure by being able to rotate about the pins. The locking devices provide the container with the capability to carry loads by rigidly securing the corner posts and the supporting structure of the container when the corner posts are in an upright position.
There are many types of prior art folding structures and locking devices. One typical type of folding structure includes thick steel plate disposed on the lower ends of the corner posts, inserted in the supporting structure of the container and attached via pins, allowing itself to be folded down by having the corner posts rotated about the pins. This type of folding structure, however, either complicates the container structure for having to conduct special arrangement on the structure to make room for the folded down corner posts, or has to accept higher height and bulky size in transportation and storage empty of cargo for having to stack the folded corner posts upon the corresponding structure of the container. The locking device can be a taper pin or a square pin equipped with a hammer, which hammers the pin into the corresponding aperture of the corner post and the container structure, facilitates the close attachment of the corner post, the pin and the bottom side rail, and further provides a block to prevent the pin from going loose. But this type of locking device is too bulky and has to be disposed on the end of the container, thus prevents other structures from being arranged on the end of the container, and leaves few chance to reduce the end thickness of the container.